Heat sealing device



Jan. 7, 1941.

H. E. HALLMAN HEAT SEALING DEVICE Filed Sept. 1, 191 s 2 Sheets-Sheet 1 INVENTOR. avoid 31' qllman Ju V 2441444., 4L, ATTORNEYS H. E. HALLMAN 2,227,497

HEAT SEALING DEVICE Filed Sept. 1, 1958 2 Sheets-Sheet 2 INVENTOR. 11' arold Hallman -40 ATTORNEY6.

Patented Jan. 7, 1941 UNITED STATES PATENT OFFICE 9 Claims.

My invention relates to the art of makingbags of paper or other similar flexible material which has been previously coated on one or both sides with wax, paraffin, or a moisture proof coating of a similar nature in order to render it resistant or impervious to grease and moisture. More specifically my invention relates to an apparatus and a method for sealing bag bottoms formed by a bottom overlap of wax coated paper.

Many attempts have been made to devise proper machines for sealing the bottoms of wax coated paper bags, but, becauseof the inherent difficulties attendant in operating with a material of this nature, such machines have been for the large part commercially impractical.

It is necessary to apply suflicient heatso that the glue placed on the wax coated paper can penetrate down into the paper when the heat melts the wax to secure a proper joint. However, when pressure is applied directly on the heated spot, the glue is squeezed out so that a good joint cannot be secured. However, when pressure is not employed, a proper sealing of the bag cannot be efiected, nor a true moisture proof seal be obtained.

I have devised a novel apparatus whereby I obtain an entire water and moisture proof seal of the bag bottoms and simultaneously effect a solid grip between the body of the bag and the overlap which forms the bag bottom.

My apparatus comprises a roll in which is placed a block having a cut out center portion, the block containing a heater preferably of the cartridge type which heats the entire block and is adapted to convey heat across the cut out section. This cut out block pressure unit is adapted to contact the'bag bottom so that the cut out portion is superimposed over the glue line and the pressure portions of the block press on the adjacent areas to form a heat seal of the wax coated paper.

By means of this machine and its method of employment the bag bottom is well pressed during the heating operation so that a good heat seal is obtained, while, at the same time, sufficient heat is imparted to the glue and the wax surrounding it so that the wax melts and the glue can penetrate to the paper which it is desired to bond. Further, the pressure units that 5 perior seal.

It is the object of my invention to provide a novel machine for effecting the heat sealing of wax coated paper. 7

It is a further object of my invention to provide a novel machine which effects the sealing of wax coated paper coated with glue by the simultaneous application of pressure to. the non-glue areas and heat without pressure to the glue area.

It is a further object of my invention to provide 10 a machine comprising a heated block having a cut out portion,the block adapted to press a bag bottom with the out out portion being superimposed over the glue line of the bag bottom.

vide a novel machine comprising a roll carrying a pressure block heated by a cartridge heater,

the pressure block having a cut out center portion, which cut out center portion is superimposed over the glue line of a bag bottom and the pressure portions of the block being superimposed over the non-glue areas of the bag bottom.

Further objects of my invention will be brought out in the following description of my invention.

In the drawings, Figure 1 is a combination cross-section and perspective view of the ma-' chine of my vinvention.

Figure 2 is a cross section taken along the line 2-2 of Figure l.

Figure 3 shows the bag that is sealed with the machine of my invention.

Figure d is a cross-section taken along the line 4-4 of Figure 3 and shows in diagrammatic detail the folded over bag bottom with the glue line in relative position with respect to the pressure block shown in dotted lines.

Figure 5 is a perspective view of a modified form of a pressure block in reversed position to more clearly illustrate its structure. In this modified form there is a provision for crimping along the bottom of the bag.

Figure 6 is a perspective of a bag having a crimped bottom pressed by the crimping pressing block shown in Figure 5.

Referring now more specifically to the drawings, in Figure 1 is shown a bag l drawn forward by the advancing rolls 2 and 3 in the direction indicated by the arrow. The bottom of the bag 4 is shown at the forward position under the pressure block Ill. Pressure block In is composed of the pressure portions H and I2 and the cut away portion 13. In the pressure block W is a cartridge heater I5 composed of the coil l6 wound around the insulated rod ll. Electricity 10 supplied to the cartridge heater and the assembly of the roll and cartridge heater. Extended from" the shaft 30 is the commutator on which rides the brushes 4| and 42 in the grooves 43 and 44. Electricity is supplied to the brushes 4| and 42 through the wires 45 and 46. At the sides of the cartridge heater are insulating members 48 and 49. The shaft 30 is set in the bearings 50 and SI and rides in the bushings 52 and 53. The lower roll 35 is similarly set in bearings.

In Figure 3 is shown the bag I with .the folded over portion 66 and the dotted lines show the glue line 6|. The longitudinal seam of the bag is indicated by the overlap 63.

In Figure 4 the end of the bag in its relation to the pressure block is shown in detail. There can be seen the glue line 64 and its relative position beneath the cutaway portion of the pressure block l0 shown in dotted lines. The pressure portions H and I2 heat seal the bottom of the bag at 66 and 61.

As set forth hereinbefore, the pressure block I I may be so formed, as 'by corrugations, as to exert a crimping action and thus crimp the bottom of the bag which it presses. Further the pressure block I! may in certain instances be reduced to a minimum width. Such construction is employed when a suflicient heat and pressure seal is obtained by the lower pressure block and sufficient adhesion is obtainedby the added adhesive. 40 In other words, instead of employing two pressure areas and a non-pressure area, simply a pressure area and a non-pressure area may be employed.

In Figure 5 there is shown a pressure block 45 I0 heated .by a cartridge heater H. The pressure block has a pressure member 12 with crimping corrugations I3 running therein. On the bottom of the pressure block and positioned at the other end from the crimping member is a relatively so thin pressure member 14. The pressure members 12 and 14 are separated by a cut out section 15 which is adapted to be positioned over the line of adhesive on the bag bottom, as shown in Figure 4. The heater H heats up the entire pres- 55 sure block, and the heated crimping member 12 readily crimps the extreme bottom of the wax coated paper bag. The entire pressure block being heated, heat is transmitted through the cut out section 15 directly .to the section of the wax 6o coated paper which carries the adhesive and melts the wax coating of the paper there so that the heated adhesive strikes through to firmly bond the fibres of the paper in that area.

In Figure 6 is shown a bag 80 with a bottom 8| comprising a crimped extreme lower end 82, glue line 83 and a heat sealed relatively narrow strip 84. Suflicient adhesion is obtained by the use of crimping 62 and the heat permeated adhesive 63 so that only this thin wax to wax seal 84 is required at the top of the bottom of the bag. The crimping of the'bottom being effected by means of a heated crimping member securely and efiectively seals the extreme bottom of the bag so that a strong and moisture proof seal is obtained.

I shall now describe the operation of my machine in detail. The bag i is fed forward through the advancing rolls 2 and l which bring its forward end 4 in the position shown in Figure 4 be neath the pressure block "I. The movement of the bag and the rolls is so coordinated that the line position of the pressure block shows the manner ofengagement of the bag. The glue has previously been placed on the bag before the folding over of the bag bottomdn an operation -which is not being described here in detail since it is well known in the art.

As the bag moves forward under the pressure block the pressure portion ll first tightly presses the portion of the bag indicated there as 66 in Figure 4 during which time heat is being exerted through the pressure portion II to effect a thorough heat sealing. Simultaneously and subsequently heat is transmitted through the block by convection and radiation to the wax paper in the area of the glue 64.- This heat serves to melt the wax causing the glue to penetrate through the paper fibres and effect a bond therewith.

Thereupon the pressure portion ll presses upon the paper at the area 61 causing athorough heat seal of the wax at that point.

In the seal of the bag bottom thus formed a strong paper to paper seal is eifected by means of the glue 64 striking through the melted wax which covers the paper. At the same time a mois. ture proof seal is effected at the portions 66 and 61 by the dual pressing action of the pressing pontions of the pressure block. The particular shape of the pressure blocks makes it impossible for the glue 64 which is in a fluid state to squeeze out, the portions H and I2 acting as blocks to the passage of the glue. By means of this simple construction a strong and impenetrable seal is quickly effected on [the bag bottom. As has been indicated the electricity is supplied by means of a commutator and brush arrangement through the center of the shaft to the cartridge heater in this pressure block.

If desired, the pressure block may have the pressure portions II and I2 duplicated on the side of the pressure block, thus forming a four square pressure extension with a center cut out. In many cases this arrangement is preferable to insure against any squeezing out of the glue and to obtain a continuous heat seal about the bottom of the bag.

In lieu of the cartridge heater shown in the block any suitable heating means may be employed to raise the temperature of the block so that the pressure portions shown at I I and I2 apply simultaneous heat and pressure to the wax coated paper while heat is transmitted over the cut away space to melt the wax adjacent the glue line.

Although I have shown a bottom drum or an engagement of the bottom of the bag in coaction with the pressure block, manifestly I may employ any suitable coacting device as .for example a travelling tape. Further, although I have shown but one pressure block set in the drum I may employ a multiplicity of such units.

One of the principal features of my invention resides in the use of the pressure block having a cutaway center portion through which an intense heat is transmitted to the wax coated paper adjacent the glue without pressure. The surrounding pressure eifecting the heat seal serves simultaneously to trap the glue and tends to force it into contact with the paper.

Although I have discussed apparatus and methods oi my invention particularly with regard to wax coated paper, it is to be understood that I use the term "wax coated paper" by analogy only ii and that I intend to cover all sheet material having a heat sensitive coating that may be employed in the manufacture of articles of the class de-- scribed. Thus I couid employ a Cellophane base sheet material with awax or any heat sensitive l coating or I could employ any suitable sheet material with any coating material with which a satisfactory bond cannot be eil'ected by an added adhesive. Thus in the claims that follow it is to be understood that such term "wax coated paper" is used as representative of the class of equivalcuts.

The application of this invention is not limited to the bag bottom sealing but is applicable to any problem wherein it is necessary or desirable to obtain a heat seal simultaneously with a glue penetration through melted coating. As can be seen the construction shown is capable of considerable modification and I intend to be limited only by the appended .claims.

I claim:

1. An apparatus for sealing wax coated papers carrying adhesive wherein it is necessary to melt the wax to allow the adhesive to strike through to the paper comprising a rotatable body carrying W a recessed pressing member having marginally positioned pressure means, means for heating said recessed pressure means, and a resilient member adapted to coact with said recessed pressing member so that a positive heat and pressure is applied to the wax coated paper by the marginally positioned pressure means and heat without pressure is applied to the area of wax coated paper carrying the adhesive thus melting the wax and causing the adhesive to strike through to the paper. so 2. An apparatus for sealing wax coated papers carrying adhesive wherein it is necessary to melt the wax to allow the adhesive to strike through to the paper comprising a recessed pressing member having marginally positioned pressure means, it means for heating said recessed pressure memher, the recessed portion of said pressing memher being positioned centrally, and a resilient member positioned to cooperate with. the marginally positioned pressure means in pressure contact applied to the wax coated paper by the marginally positioned pressure means and heat without pressure is applied to the area of wax coated paper carrying the adhesive thus melting the wax and causing the adhesive to strike through to the WW 3. an apparatus for sealing wax coated papers carrying adhesive wherein it is necessary to melt w the wax to allow the adhesive to strike through to the paper comprising a rotatable body carrying a recessed pressing member, means for heating said recessed pressure member, the recessed portion of said pressing member being positioned centrally. es and marginal pressing members at the edges of said recessed portion, the recessed central area being adapted to apply heat without pressure and the marginally positioned pressure members being adapted to simultaneously apply pressure with 70 heat, and a resilient member adapted to coact with said recessed pressing member so that a positive heat and pressure is applied to the wax coated paper by the marginally positioned pressure means and heat without pressure is applied to the area ill of wax coated paper carrying the adhesive thus relation so that a positive heat and pressure is melting the wax and causing the adhesive to strike through to the paper.

4. An apparatus for sealing wax coated paper carrying adhesive wherein it is necessary to melt the wax to allow the adhesive to strike through 5 to the paper comprising a recessed pressing member having marginally positioned pressure means, means for heating said recessed pressure member, the recessed portion of said pressing member being positioned centrally, and a synchronously rol0 tating pressure member rotating in pressure contact with said recessed pressing member and adapted to coact with said recessed pressing member so that a positive heat and pressure is applied to the wax coated paper by the marginally posi- 15 tioned pressure means and heat without pressure is applied to the area of wax coated paper carrying the adhesive thus melting the wax and causing the adhesive to strike through to the paper.

5. An apparatus for sealing wax coated papers 2 carrying adhesive wherein it is necessary to melt the wax to allow the adhesive to strike through to the paper comprising a recessed pressing memher having marginally positioned pressure means, means for heating said recessed pressure mem- 25 her, the recessed portion of said pressing member being positioned centrally, and a synchronously rotating rubber pressure member rotating in pressure contact with said recessed pressing member and adapted to coact with said recessed pressing 30 member so that a positive heat and pressure is applied to the wax coated paper by the marginally positioned pressure means and heat without pressure is applied to the area of wax coated paper carrying the adhesive thus melting the wax Bil and causing the adhesive to strike through to the paper.

6. An apparatus for sealing wax coated papers carrying adhesive wherein it is necessary to melt block and being substantially parallel with said recess, a cartridge heater located within said pres- 50 sureblock, and a cooperating and synchronously rotating resilient pressure means positioned to rotate in pressure contact with said projecting pressure members.

7. Anapparatus for sealing wax coatedpapers 55 carrying adhesive wherein it is necessary to melt thewax to allow the adhesive to strike through to the paper comprising a rotating member, a pressure block mounted on said rotating member,

a transverse recess extending across the external face of said pressure block substantially centrally thereof, projecting pressure members positioned on said pressure block and adjacent said transverse recess, said projecting pressure members extending across the external face of said pres- 5 sure block and being substantially parallel and coextensive with said recess; a cartridge heater-located within said pressure block and a cooperating and synchronously rotating rubber covered roll positioned to rotate in pressure contact with said projecting pressure members.

8. An apparatus for sealing wax coated papers carrying adhesive wherein it is necessary to melt the wax to allow the adhesive to strike through to the paper comprising a rotating member, a pres- 7 sure block mounted on said rotating member, a transverse recess extending across the external face of said pressure block substantially centrally thereof, a forwardly positioned projecting pressure member and a rearwardly positioned projecting pressure member on said pressure block a. and adjacent said transverse recess, said projectand a cooperating and synchronously rotating resilient pressuremeans positioned to rotate in pressure contact with said projecting pressure members. I

9. An apparatus for sealing wax coated papers carrying adhesive wherein it is necessary to melt the wax to allow the adhesive to strike through to the pa er comprising a rotating member, a".

pressure block mounted on said rotating member, a transverse recess extending across the external face of said pressure block substantially centrally thereof, a forwardly positioned projecting pressure member and a rearwardly positioned projecting pressure member on said pressure block and adjacent said transverse recess, said projecting pressure members extending across the external face of said pressure block and being substantially parallel with said recess, the forwardly positioned projecting pressure member in the path of travel of the rotating member having a crimping surface and being of substantially greater width than the rearwardly positioned projecting pressure member, a cartridge heater located within said pressure block, and a cooperating and synchronously rotating resilient r pressure means positioned to rotate in pressure contact with said projecting pressure members.

HAROLD E. HALLMAN. 

